The identification of friendly ground-based equipment and/or vehicles (hereinafter referred to as vehicles) from a military aircraft is of paramount concern in combat operations. Accordingly, numerous Identification Friend or Foe (IFF) systems have been developed to enable friendly vehicles to clearly indicate their affiliation with associated friendly aircraft.
A simple example of an IFF system is constant-on, visual recognition system in which each vehicle is constantly emitting a visual (friendly) signal that may be seen by the pilots of the aircraft flying overhead. Other IFF systems that are more complex in nature include interrogation IFF systems in which ground-based vehicles emit a (friendly) infrared or radio signal only when in receipt of an acceptable interrogation signal from overhead aircraft. Security for both simple and complex IFF systems is typically achieved by coding the interrogation and friendly signals so that opposing forces cannot detect and/or duplicate same. Representative examples of such IFF systems are disclosed in U.S. Pat. No. 4,814,769 issued to Robin et al. on Mar. 21, 1989, U.S. Pat. No. 4,837,575 issued to Conner, Jr. on Jun. 6, 1989, and U.S. Pat. No. 4,862,176 issued to Voles on Aug. 29, 1989. Each of these prior art IFF systems provides a method/system for identifying a vehicle as a friend or foe.
While identifying a particular vehicle as friendly is paramount at the field operation level, this recognition does not provide enough information for command level observation of the larger theater of combat or training operations. At the command level, it is also desirable to know a vehicle's identity and position in order to evaluate current conditions and plan for the future.